Liquid fuel burner



May 28, 1963 J. H. KIDWELL LIQUID FUEL BURNER 2 Sheets-Sheet 1 Filed Feb. 24, 1960 May 28, 1963 J. H. KIDWELL LIQUID FUEL BURNER 2 Sheets-Sheet 2 Filed Feb. 24, 1960 FIG.2

FIG.3

FIG. 5

INVENTOR. John H. Kdwell ATTORNEY United States 3,091,2ss LEQUED FUEL BURNER .lohn H. Kidwell, Canton, Sirio, assigner to The Babcock & Wilcox Company, New York, N.Y., a corporation of New Jersey Filed Feb. 2.4, 1960, Ser. No. 10,682 12 Claims. (Cl. 158-76) This invention relates generally to liquid fuel burners, and more speciiically to an improved liquid fuel atomizer and burner arrangement incorporating the same, and control therefor.

Heretofore, experience with known liquid fuel burners has shown that atomization tends to break down at oil rates below one-tenth load.

Therefore it is an object of this invention to provide an improved atomizing liquid fuel burner having a high turn-down ratio, as for example 30 to l, while employing only moderate oil pressures.

Another object is to provide a plunger-type liquid fuel atomizer in which the volume of the whirl chamber and the amount of liquid fuel introduced thereinto are simultaneously controlled, with means constructed and arranged for also introducingy an assisting uid into the whirl chamber to promote atomization of the `fuel .therein at low loads.

Another object of this invention is to provide a liquid fuel atomizer with means for varying the rate of liquid fuel supplied thereto in combination with a variable volume mixing or whirl chamber with means for introducing a gaseous fluid thereinto to enhance atomization of the liquid-fuel.

Still another object is to provide means for automatically controlling the point at which assisting iiuid is introduced into the liquid-fuel atomizer for enhancing the -atornization of the fuel.

And, another object is to provide a liquid-fuel burner with means for assisting atomization of the fuel and means .co-operating therewith for enhancing the subsequent mixing of the atomized fuel with combustion air to attain a very high turn-down ratio.

The yforegoing objects, and other features and advantages are attained by a liquid-fuel burner having -a liquidfuel atomizing means disposed along a longitudinal axis of the burner and having its discharge end extending into an air register which is disposed adjacent a burner port of a furnace wall. The atomizing means comprises a fuel supply barrel and includes an atomizer cage which denes a whirl chamber that terminates in a restricted discharge orice connected to the end of the barrel. The cage is spaced inwardly of the 'barrel and is provided with a series of apertures extending substantially tangentially of the whirl chamber for allowing the passage of liquid-fuel from the barrel to the whirl chamber, atomization of the fuel being effected by the centrifugal or whirling action created therein. A plunger means is provided for simultaneously varying the volume of the whirl chamber and for valving the apertures to control the amount of liquid-fuel entering the whirl chamber in accordance with changing load conditions.

According to this invention, the plunger means is provided with means for introducing a gaseous iluid into the whirl chamber to assist in the atomization of the fuel therein at low loads. To enhance subsequent mixing of the atomized fuel with the combustion air a sleeve or central duct is spatially disposed about the fuel atomizer within the air register to divide the -air passing therethrough into inner and outer air streams. Means are provided for imparting a whirling motion to each of the air streams. A further means is provided to direct a major portion of the inner air stream toward the periphery of the central duct and lthereby create a relatively low 31,991,233 Patented May 28, 1963 velocity zone at the center of the burner to produce a stable lflame. Included in the burner arrangement is a control circuit to automatically control the point at which the uid for assisting atomization of :the fuel cuts in and out.

A feature of this invention resides in the provision of a burner arrangement in which a very substantial increase in the turn-down range thereof is attained.

Another feature resides in the provision of a novel plunger-type liquid-fuel atomizer in which the plunger is provided with means for introducing an assisting fluid into the whirl chamber .to enhance atomization of the fuel therein.

Another feature resides in the provision for progressively decreasing the cross-sectional area of the f-uel inlet openings spaced longitudinally along the length of the whirl chamber cage as they approach the whirl chamber discharge oritice.

Another feature resides in the provision of means disposed about the fuel barrel and spatially disposed within the central duct for directing a major portion of the inner air stream outwardly toward the periphery of the duct.

The various :features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a 'better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and `descriptive matter in which there is illustrated and described a preferred embodiment of the invention.

In the drawings:

FIG. 1 is a sectional side View of a liquid-fuel burner embodying the present invention with the control circuit for operating the same schematically illustrated.

FIG. lA is an enlarged sectional view taken along line 1A-1A of yFIG. 1.

FIG. 2 is an enlarged detail of the atomizer whirl chamber cage.

FIG. 3 is a left-hand end view of FIG. 2.

FIG. 4 is a detailed sectional side view of the improved plunger in accordance with this invention.

FIG. 5 is an end view of FIG. 4.

Referring to FIG. ll, numeral 101 is a wall of a furnace chamber which is provided with a burner port or opening y12. As shown, the inner surface 13 of the port |12 opening to the furnace chamber is truste-conical in shape and diverges toward the furnace side 1v1 of the wall l0 at an angle of approximately 45. Spaced from the furnace wall 10 is a burner wind-box casing 14 Which defines a passageway `15 through which combustion air is delivered from a suitable source to the burner 16 by a blower which is not shown. The burner casing 14 is provided with .an access opening 17 disposed in axial alignment with the burner port 12. A suitable access door 18 closes the opening 17.

The air register 19 of the burner is disposed within the wind-box 15 and is located adjacent the burner port 12. As shown, the air register `19 consists of a tubular housing 2li having co-axially disposed open annular end portions deiining an air inlet 21 and an air outlet 22.

The co-axial outlet 22 is more particularly defined by a frusto-conical transition section 23 which converges toward and connects with a cylindrical sleeve 24 extending into burner port 12 in the furnace wall 110. A frustoconical section 25 is connected to the inboard end of sleeve 24 and forms with the surface 13 at their junction a restricted throat section 26.

An annular ange or collar plate `27 circumscribing sleeve 24 is disposed adjacent the furnace wall 10` and secured thereto to support the air register '19.

The liquid-fuel or oil burner further includes a fuel supply barrel 28 extending lalong the longitudinal axis of the air register 19. The barrel 28 is supported in a tubular distance piece 29, which in turn, is supported at its outer end in a bearing 30 located centrally of the access door 18. The inner end of the barrel extends into the air. register 19.

vConnected to the outer end of the distance piece 29 is a readily detachable coupling housing 31 for connecting the barrel 28 to a source of liquid-fuel (not shown). T-he housing 31 is provided with a yoke or clamp 32 by which it is secured to the distance piece '29. In the housing 311 is a bore 33 forming a liquid-fuel passageway which has one end connecting with a suitable fuel line 79 and the other end thereof opening to a chamber 34 into which the end 2SA of the supply barrel 28; is threaded, :thereby placing the fuel supply :barrel 2S in communicationl with a fuel supply (not shown).

The housing 31 isralso providedl with a second passageway 35 which is adapted to connect to a suitable source of fluid, as for example compressed air, for reasons to be hereinafter set forth.

Connected to the inner :end 28B of barrel 28, in accordance with this invention, is an improved atomizing means. As shown in FIG. 2, the atomizing means comprises an atomizing cage 36, in the form of a hollow cylindrical body member defining at its inner portion an atomizing whirl chamber 37. The innermostportion of the whirl chamber 37 converges to define a restricted discharge orice 38 in the end lwall thereof. As shown in FIGS. l and `lA, the cylindrical body of the atomizer cagev 36 is disposed in longitudinally spaced relationship with respect to the innery surface of the barrel 28 to define. an annular -ow path 49 therearound. A laterally extending flange 36A integrally formed with the body of cage 36 is arranged to abut `the inner end 28B of barrel 28. A threaded cap 39having an inturned llange 39A which engages flange 36A of the `atomizer cage provides the means by which the cage 36. is held in place at the end of barrel 28.

As shown inY FIG. 2, the cylindrical cage body 36 is provided vwith a plurality of spaced apertures 40 disposed in rows at intervals about the cage circumference and through which fuel owing within the barrel 28 to annulus 49 is introduced into whirl Vchamber 37.- As `shown in FIGS. 12. and 3, the apertures 411V in each of the rows have their axes disposed substantially tangentially with respect to the whirl chamber 37, with the cross-sectional area ofthe apertures y4,0 in each row progressively reduced iny size as they approach the discharge orilice 38. Thus it is to be noted that as the fuel flows from barrel 28,y and into theV Whirl chamber 37 through the tangentially disposed. apertures 40, a whirling motion is im,- parted .to the fuel within the` whirl chamber to effect mechanical atomization.

To provide flexibility in burner capacity the amount of fuel. introduced may bev varied` without changing the pressure and temperature conditions( of the fuel, by means ofaplunger provided to simultaneously vary both the whirl chamber volume, and the valving of apertures 4j through whichfuel is introduced into the whirl chamber. As shown, the plunger means comprises a plunger shaft `41 which extends through the housing 31 and coaxially through the connected barrelZ-S, to connect with plunger 42 ,the` latter being adapted to beslidably received within the whirl chamber 37.

The apertures `49| in the atomizer cage are sized so that, at aconstant oil supply pressure, flow rate is essentially a linear function of plunger travel. This makes it relatively simple to parallel operation of the burner with other controlled variables, suchuas combustionv air flow.

A` coilspring 43, disposed about the outer end ofA shaft 441, functions` normally to cause the shaft 41 and connected plungerl 42 to positionthe plunger 42 outwardly Cil or away from the whirl chamber orifice 38. As shown, the spring 43 is retained -between the wall 311A of the housing 31 and a collar 44 -xed to the rearward end of the shaft 41.

Heretofore in plunger-type liquid fuel atomizing burners breakdown of fuel atomization was experienced at low loads with consequent loss in combustion efficiency. It has been discovered that the turn-down ratio of a plunger-type mechanical atomizer can be substantially increased by introducing a Huid, such as 'G0-100 p.s.i. compressed air, into the whirl chamber to assist fuel atomization when the burner is operating in the lower load range.

In accordance with this invention, means for effectively increasing the turn-down ratio in an oil burner having a plunger-type atomizer is attained by providing :the plunger shaft 41V with an axial bore 41A which connects to and is in registry with air distributing bore 42A in plunger 43 as shown in FIGS. `11A and 4. Apertures 42Bformed in the end wall of plunger 42 serve to provide a fluid flow path by connecting the air distributing bore 42A of the plunger 42 with Ithe whirl chamber 3-7'. Preferably the apertures 42B are directed in the direction of the whirl in chamber 37. Means are provided for introducing the requisite amount of air through the plunger shaft 41 and connected plunger 42 to the whirl chamber 37` to assist atomization, in response to conditioned control impulses.

Referring to FIG. l, the end of the plunger shaft extending through the housing 31u is arranged to reciprocate within an axially aligned, air chamber 45, disposed within housing 311-, and in communication with air passageway 35. `During low load operation, at which times atomization -tends to break down, air directed to the air chamber 45 from passageway 35 is introducedin-to the bore 41A of the shaft 41 through one or more radially extending apertures 46 located in that portion ,of the shaft registering with the air chamber 45. Thus the air is directed` through the plunger shaft bore 41A to bore 42A of thel plunger from whence it is discharged into the whirl chamber through openings 42B in the face ofthe plunger to assist in atomization of the fuel.

To promote turbulence within the air stream andthereby enhance the subsequent mixing of the atomizedY fuel upon its discharge through orifice 38with combustion air, a whirling motion is imparted to the air entering. the register by a plurality ofy radiallyrdisposed, adjustable vanes in` air doors 51. 1n addition `a central sleeve or duct 50 is spatially disposed about the fuel supply barrel 218 within the air register 19 to divide the air into inner and outer air streamsA to provide intimate contact of the fuel and air. The air doors 51 aresimultaneously adjustable over a range between. fully open and fully :closed position and thereby control andproportion the amount of air entering the air register. As` shown, each air door 531 is pivoted at its ends between afrusto-conical collar SZ connected to a sleeve extension 53 of bearing 30 and an outer ring 54 connected to the inlet end 21 of the housing: 20. Means for controlling the positioning of theair doors 51 comprises a beveled gear `55 connected to the lower pivot 56 of each door 51. A master or bull gearl 57 connected to a sleeve 58, rotatably mounted aboutV the distance piece 29, is arranged, in meshing relationship with gear 55 on each of the doors 51. Actuation of thebull gear 557 is had througha gearv sector 59v secured to the bull gear sleeve 458. Thevgear sectorv 59 -in turn is connected in meshing relationship to aV pinion 60 .fixed-to the end of a shaft 6 1 which is equipped with a suitable operating means, as for example a crank or handle (not shown). Thus positioning of the `doors 51 is readily accomplished through the gearing-crank arrangement described.

To further promote the whirling movement, o f the inner air stream, a plurality of vanes 62-are disposed about the distance piece 29, adjacent the inlet end of the central duct 5t?. Vanes 62 are preferably xed at a predetermined angle with respect to the distance piece 29 and the central air duct 50.

A major portion of the air owing through the duct 50 is directed to its outer periphery by a frusto-conical defiector 63. The deflector is attached to ythe distance piece 29, within the duct 50. This air ow pattern creates a relatively low velocity zone at the center of the burner and thus promotes burner `llame stability over the entire range of fuel flow. If desired, a portion of the air may -be bled through defiector 63 through one or more apertures 64 in `deflector 63. Thus the central duct arrangement described provides an air -ow-fuel ow pattern which effects good ignition stability over a wide load range, ybut with the burner parts sufficiently removed from the oil spray to eliminate wetting and coking often encountered on wide range burners.

Automatic control for the burner described may be attained by an electrically, hydraulically, or pneumatically energized control circuit. However in FIG. 1, the illustrated circuit 70 is electrically operated and includes a combustion controller 71 which receives a control impulse through lead 72 originating, as for example, from a steam pressure regulator (not shown), or from another suitable indicator responsive to varying load conditions. Connected in parallel with the combustion controller 71 is a linear action drive motor 73 to actuate a reciprocating drive push rod 74 which is in operative engagement with the plunger shaft 41, and a switch 75 which actuates solenoid air valve 76 to control the ow of air in line 81 leading to the air passageway 35 of the coupler 31. If desired, a check valve 77 may be disposed in the air line 81A leading from the solenoid valve 76 to the air passageway 35 of the coupler housing 31.

Flhe fuel oil is introduced into the oil passageway 33 of the coupler 31 through a fuel line 79 which has disposed therein an oil pressure regulating valve 80 for insuring a substantially constant oil pressure throughout the operation of the burner.

As shown, the drive unit 73 is connected to a yoke 99 which can be pivoted about pivot 100 to facilitate removal of the atomizer assembly.

The operation of the control circuit is as follows:

At full load operation of the burner .a control impulse received by the linear drive motor 73 causes the drive push rod 74 to be retracted to inoperative position, that is to the extreme left as viewed in FIG. 1. The plunger shaft 41 and connected plunger 42 follow the movement of the push rod '74 due to the action of the shaft spring `43 and the force exerted by the oil pressure on the face of the plunger 42. Movement of the plunger 42 to the extreme left opens all of the tangentially drilled holes or apertures 40 in the wall of the atomizer cage 36, and allows the full ow of oil into the atomizer whirl chamber 37, in which the oil proceeds at an increasing rate of spin to the discharge orifice 38. As the combustion controller 71 calls for less oil, the appropriate control irnpulse or signal is transmitted to the motor 73 and causes the drive push rod 74 to be moved to the right. The action of the push rod 74 causes the plunger shaft 41 and connected plunger 42 to move to the right to effect a progressive valving or shutting off of the holes 40 in the atomizer cage, thus reducing the ow of oil entering Whirl chamber 37.

At some predetermined low load, e.g. at 1/10 load, the control impulse is sent through lead S2 to actuate the switch 75 controlling the action of the solenoid air valve 76. When the switch 75 is energized, the air valve 76 opens to .admit assisting air to the atomizer. With the air valve 76 open, lthe air flows from the supply line 81, through the air valve 76 and check valve 77 in line 81A to the air passageway 35 of the burner coupler 31. From the passageway 35 the air enters the air distributing chamber 34 from whence it ows through apertures 46 to the bore 41A of the plunger shaft 41. The air thus iiows to the plunger 42 from whence it is introduced into the atomizer whirl chamber 37 through openings 42B located in the face of the plunger 42.

The only requirement regarding the load at which `the air assist is introduced into the whirl chamber 37 is that the oil pressure in the whirl chamber must be less than that of the air pressure.

As the load is increased the operation of the control circuit proceeds in the reverse sequence.

If desired, .a manual control is provided for adjusting the position of the plunger 42. The manual control comprises simply a threaded handjack by which the actuation of the plunger shaft 41 may be attained by manual rotation of the handjaclt 90 upon disengagement of a releasable pin connection which connects push rod 74 to drive 73. llhus rotation of the handjack in one direction advances the push rod 74 and plunger into the whirl chamber and rotating the handjack in the opposite direction retracts the same.

To prevent the back flow of gases through the distance piece 29, a collar 9S is disposed about the supply barrel 28, to form a seal about the outer end of the distance piece. As shown a spring 96 urges the collar in sealing engagement against the end of the distance piece.

While in accordance with the provisions of the statutes there is illustrated and described herein the best form and mode of operation of the invention now known to the inventor, those skilled in the art will understand that changes may be made in the form of the apparatus disclosed without departing from the spirit of the invention covered by the claims, and that certain features of the invention may sometimes be used to advantage without a corresponding use of other features.

What is claimed is:

l. A liquid fuel atomizcr comprising means defining a cylindrical whirl chamber having a restricted discharge orifice, means including a plurality of openings longitudinally spaced along the length of said whirl chamber for supplying liquid fuel to said whirl chamber, and a plunger closely fitting within said whirl chamber and axially movable for varying the volume of said whirl chamber and for valving said openings to control the amount of liquid fuel entering said whirl chamber, said plunger having a passage therethrough, .and means for introducing a fluid through said passage into said whirl chamber to assist atomization of the fuel during low load operation.

2. A liquid fuel atomizer comprising a tubular barrel, an atomizer cage defining a cylindrical whirl chamber having a restricted discharge orifice connected to one end of said barrel, said cage having a plurality of openings longitudinally spaced along the length thereof, said openings extending tangentially of said whirl chamber, means for supplying liquid fuel to said barrel whereby 'the fuel is introduced into said whirl chamber through said openings, and a plunger closely fitting within said atomizer cage and axially movable for varying the volume of said whirl chamber and for valving said openings to control the amount of liquid fuel entering said whirl chamber, said plunger having a passage means for introducing a gaseous uid into said whirl chamber to assist atomization of the fuel therein .and means for cutting in a supply of said uid to said plunger at a predetermined low load operation of the atomizer.

3. A liquid fuel atomizer comprising a tubular barrel, an atomizer cage connected to one end of said barrel and spatially disposed therein, said cage defining a cylindrical whirl chamber having a restricted discharge orice and having a plurality of openings longitudinally spaced along the length of said whirl chamber, said openings extending tangentially of said whirl chamber for mechanical atomization therein, means for introducing a liquid fuel to said barrel and through said openings to said whirl chamber, a plunger slidably mounted and closely fitting within said cage, .and means for actuating said plunger to vary the volume of said whirl chamber and to valve said openings to control the amount of liquid fuel entering into fsaid whirl chamber, said plunger having a passage therethrough, and means for introducing .a gaseous fluid `through said passage into said Whirl chamber to provide 'combined duid-mechanical atomization of the fuel during predetermined low load operation.

4. An improved liquid fuel burner comp-rising an air register for receiving combustion air, a sleeve disposed in Isaid air register for dividing said combustion air into an inner and outer air stream, a barrel extending along a ylongitudinal axis of the burner, said barrel being spatially disposed in said sleeve, means for supplying liquid fuel to said barrel, an atomizing means connected to one end of the barrel, said `atomizing means including an atomizer cage defining a cylindrical whirl chamber having a restricted fuel discharge orifice, said cage having a plurality of openings longitudinally spaced along the length thereof through which liquid fuel from said barrel is in- .troduced into said whirl chamber, and a plunger slidably .mounted and closely fitting within said whirl chamber and movable therein for varying the volume of said whirl chamber and for valving said openings to control the tamount of liquid fuel entering into said whirl chamber, -said plunger having a passage therethrough, `and means for introducing a gaseous fluid through said passage into -said whirl chamber to assist atomization of lthe fuel theiein during pre-determined low load operation only.

An improved liquid fuel burner comprising `an -air register for receiving combustion air, said register having coaxially disposed air inlet and air outlet ends, a sleeve coaxially disposed in said air register for dividing said combustion air into an inner and outer air stream, means imparting a whirling movement to each of said air streams, a barrel extending along a longitudinal `axis of the burner, said barrel being spatially disposed in said sleeve, means for supplying liquid fuel to said barrel, an atomizing means connected to one end-of the barrel, said atomizing means including an atomizer cage defining a cylindrical whirl chamber having a restricted fuel discharge orifice, said cage .having a plurality of openings longitudinally spaced along the length thereof through which liquid fuel from said barrel is introduced into said whirl chamber, and a plunger slidably mounted and closelyliitting within said whirl chamber and movable therein for Varying the volume of said Whirl chamber and for valving said openings to control the amount of liquid fuel entering into said whirl chamber, said plunger having a passage therethrough, and means for introducing a gaseous iiuid through. said passage into said whirl chamber to assist atomization of the fuel therein during predetermined 10W load operation only of the burner.

6. A liquid fuel burner comprising `an air register for receiving combustion air, a sleeve disposed within said lair register for dividing said register air into an inner and outer air stream, means for imparting a whirling movement to each, of said inner and outer air streams, a barrel extending along a longitudinal axis of said burner, said barrel having an end portion spatially disposed in said lsleeve, an outwardly flaring impeller disposed about said lbarrel within sai-d sleeve, said impeller being arranged -to direct the whirling inner air stream outwardly toward the periphery of said sleeve, means for supplying liquid fuel to said barrel, an atomizing means connected to the end `of said barrel, said atomizing means including an atomizer 'cage -dening a cylindrical whirl chamber having a restricted fuel discharge orifice, said cage having a plurality of apertures longitudinally spaced along the length of said cage through which liquid fuel from said barrel is introduced in said whirl chamber, said apertures having their axes extending substantially tangentially of said whirl chamber and their respective cross-sectional area progressively diminished as their proximity to said orifice is increased, a 'plunger adapted to be received in said whirl chamber in a closely fitting relationship therewith, means for rendering said plunger movable in said whirl chamber for simultaneously varying the volume of Said chamber and valvingfsaidapertures to control the amount of liquid fuel entering said chamber, said plunger having a longitudinally extending bore vopening to said whirl chamber, and means for cuttingin and directing a gaseous uid through said bore to said whirl chamber to assist Iatornization of the fuel therein at a predetermined low load operation of the burner.

7. An improved liquid fuel burner comprising an air register for receiving combustion air, a sleeve ydisposed in said air register for dividing said combustion air into an inner and outer air stream, a barrel extending along a longitudinal axis of the burner, said barrel being spatially disposed in said sleeve, means for supplying liquid fuel to said barrel, an atomizing means connected to one end of the barrel, said atomizing means including an atomizer cage defining a `cylindrical whirl chamber having a restricted fuel discharge orifice, said cage having a plurality of openings longitudinally spaced along the length thereof through which liquid fuel from said barrel is introduced into said whirl chamber, a plunger slidably mounted Within said whirl chamber and movable therein for varying the volume of said whirl chamber and for valving said openings to control the amount of liquid fuel entering into said whirl chamben said plunger having means for ldirecting a gaseous uid into said whirl chamber to assist atomization of the fuel therein at low loads, and means for automatically sliding said plunger within said whirl chamber including a control circuit having a linear action drive motor operatively connected to said plunger to effeet `movement thereof, means responsive to changing load conditio-ns of the burner for energizing said circuit to actuate said drive motor, said latter means cutting in the supply of gaseous iiuid at a predetermined low load condition.

8. A `liquid fuel burner comprising an air register for receiving combustion air, a sleeve disposed within said air register for dividing said register air into an inner and outer air stream, means for imparting a whirling movement to each' of said inner and outer air streams, a barrel extending along a longitudinal axis of said burner, said barrel having an end portion spatially disposed inv said sleeve, means for supplying `liquid fuel to saidy barrel, an atomizing means connected to the end of said barrel, said atomizing means including an atomizer cage defining a cylindrical whirl chamber having a restricted fuel discharge orifice, said cage having a plurality of apertures longitudinally spaced along the length of said cage through which liquid fuel from said barrel is introduced in said Whirl chamber, said apertures having theirv axes extending substantially tangentially of said whirl chamber Iand their respective cross-sectional area progressively diminished as their proximity to said orifice is increased, a plunger adapted to be received in said whirl chamber in a closely fitting relationship therewith, means yfor rendering said plunger movable in said whirl chamber for simultaneously varying the volume of said chamber and valving said apertures to control the amount of liquid fuel entering said chamber, said plunger having a longitudinally extending bore opening to said whirl chamber, and means for directing a gaseous fluid through said bore to said whirl chamber to assist atomization of the fuel therein during low load operations.

9. A. liquid fuel burner comprising yan air register for receiving combustion air, a sleeve disposed within said air register for dividing said register air into laninner and outer air stream, means -for imparting a whirling movement to each of said inner and outer air streams, a barrel extending along a longitudinal axis of said burner, said barrel having an end portion spatially disposed in said sleeve, means for supplying liquid fuel to sa-id barrel, an atomizing means connected to the end of said barrel, said atomizing means including an atomizer cage defining a cylindrical whirl chamber having a restricted fuel discharge orifice, said cage having a plurality of apertures longitudinally spaced along the length of said cage through which liquid fuel from said barrel is introduced into said whirl chamber, said apertures having their axes extending substantially tangentially of said whirl chamber and their respective crosssectional area progressively diminished as their proximity to said orifice is increased, a plunger adapted to :be received in said Whirl chamber, means for rendering said plunger movable in said Whirl chamber for simultaneously varying the volume of said chamber and valving said apertures to control the amount of liquid fuel entering said chamber, said plunger having a longitudinally extending bore opening to said Whirl chamber, and means for directing a gaseous fluid through said bore to said Whirl chamber to `assist atomization of the fuel therein, and a control circuit for automatically controlling the operation of said burner, said circuit including a linear drive motor and a switch means connec-ted in parallel, said motor being operatively connected to said plunger, and said switch means controlling the flow of gaseous fluid to said plunger, means responsive to changing load conditions of said burner to energize said circuit for actuating said drive motor to effect movement of said plunger accordingly throughout the burner load range, and said latter means rendering said switch operative to admit said gaseous iluid to said plunger at some predeterminate low load range only.

10. An improved liquid fuel burner comprising an air register for receiving combustion air, a sleeve disposed in said air register for dividing said combustion air into an inner `and outer air stream, means for imparting a whirling movement to each of said air streams, a barrel extending along a longitudinal axis of the burner, said barrel .being spatially disposed in said sleeve, a vaneless impeller disposed about said barrel within said sleeve, said impeller ilaring upwardly and outwardly toward the periphery of said sleeve, ya housing means connected to one end of said barrel for supplying liquid fuel thereto, an atomizing means connected Ito the other end of the barrel, said atomizing means including an atomizer cage defining -a cylindrical whirl chamber having a restricted fuel discharge orifice, said cage having a plurality of openings longitudinally spaced along the length thereof through which liquid fuel from -said barrel is introduced into said whirl chamber, said `openings having their axes extending substantially tangentially of said whirl chamber, a plunger slidabl-y mounted Within said Whirl chamber and movable therein for Varying the volume of said Whirl chamber and for valving said openings to control the amount of liquid fuel entering into said whirl chamber, said plunger having a bore opening to said whirl chamber, a hollow plunger shaft connected to said plunger, said shaft extending outwardly ,beyond said housing, said housing means having a passageway connecting with said shaft for directing a gaseous fluid through said shaft and connected plunger to said Whirl chamber to assist atomization of the fuel therein, spring means normally urging said shaft and connected plunger away from said orilce, and means for automatically sliding said plunger against the action of said spring to valve said Whirl chamber including a control circuit having a linear action drive motor operatively connected to said plunger to effect the movement of said plunger, means responsive to the rate of combustion for energizing said circuit to operate said drive motor, and means cutting in the gaseous fluid supply to said plunger at a predetermined low load range only to assist fuel atomization thereat.

11. .A liquid fuel `burner comprising an outer tubular barrel, ,an inner tubular conduit disposed in space-d relationship within said outer barrel to form a flow space therebetween, means including la cap closing the outer end of said ilow space between said outer barrel and said inner conduit, an atomizer cage defining a cylindrical Whirl chamber having a restricted discharge orifice connected to lthe outer end of said outer barrel `and in communication with said inner conduit, said cage having a plurality of openings spaced talong the length thereof and communicating said Whirl chamber with said `flow space, a plunger closely fitting -Within said Whirl chamber and forming the inner end of said whirl chamber, means for supplying a liquid fuel -to said outer tubular barrel whereby the 1fuel is introduced into said whirl chamber through said openings, said plunger axially movable in said whirl chamber to Vary the volume of said whirl chamber and to valve said openings to control the mnount of liquid fuel entering said whirl chamber, :and a passage through said plunger, tand means for introducing a gaseous fluid through said passage into said whirl chamber to assist atomization of the fuel therein.

l2. A liquid atom-ize-r comprising a whirl chamber having a restricted discharge orice adapted to effect mechanical atom-ization of :a liquid fuel, means for supplying a liquid fuel into said rwhirl chamber for discharge through said orice, means including a combustion controller for regulating the flow of said liquid fuel to said atomizer, means for supplying iluid into said chamber to assist latomiz-ation of said liquid fuel, a valve means for controlling the flow of said assisting fluid to said Whirl chamber, and -a regulating means responsive to said combustion controller for opening said valve means to supply said assisting duid to said whirl chamber when the fuel flow falls below a predetermined quantity to provide combination fluid-mechanical fatomization of said liquid fuel and for closing said valve means to stop the supply of said assisting iluid when the fuel ow exceeds said predetermined quantity to provide mechanical atom-ization of said liquid fuel.

References Cited in the le of this patent UNITED STATES PATENTS q 715,044 yFisher Dec. 2, 1902 1,042,076 Breuer Oct. 22, 19i12 1,486,685 Reinhardt Mar. :1l, 192A 1,914,355 Argyle et tal. June 20, 1933 2,233,529 Herr Mar. 4, 1941 2,774,629 Noon et al. Dec. 18, 1956 2,838,103 Voorheis June l0, 1958 

12. A LIQUID ATOMIZER COMPRISING A WHIRL CHAMBER HAVING A RESTRICTED DISCHARGE ORIFICE ADAPTED RO EFFECT MECHANICAL ATOMIZATION OF A LIQUID FUEL, MEANS FOR SUPPLYING A LIQUID FUEL INTO SAID WHIRL CHAMBER FOR DISCHARGE THROUGH SAID ORIFICE, MEANS INCLUDING A COMBUSTION CONTROLLER FOR REGULATING THE FLOW OF SAID LIQUID FUEL TO SAID ATOMIZER, MEANS FOR SUPPLYING FLUID INTO SAID CHAMBER TO ASSIST ATOMIZATION OF SAID LIQUID FUEL, A VALVE MEANS FOR CONTROLLING THE FLOW OF SAID ASSISTING FLUID TO SAID WHIRL CHAMBER, AND A REGULATING MEANS RESPECTIVE TO SAID COMBUSTION CONTROLLER FOR OPENING SAID VALVE MEANS TO SUPPLY SAID ASSISTING FLUID TO SAID WHIRL CHAMBER WHEN THE FUEL FLOW FALLS BELOW PREDETERMINED QUANTITY TO PROVIDE COMBINATION FLUID-MECHANICAL ATOMIZATION OF SAID LIQUID FUEL AND FOR CLOSING SAID VALVE MEANS TO STOP THE SUPPLY OF 